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| A New Design of Digital Correlator for Johnson Noise Thermometry |
| FU Yun-feng1，QU Ji-feng1, ZHANG Jian-qiang1，2，ZHOU Kun-li1 |
1. National Institute of Metrology, Beijing 100029, China；
2. China Jiliang University, Hangzhou, Zhejiang 310018, China
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Abstract The basic principles and characteristics of cross-correlators used in Johnson noise thermometry are described. A new digital correlator is presented based on commercial analog-to-digital converters and Lab VIEW software for the measurement of the thermal noise. High-precision synchronous dual-channel-sampling has been achieved by adjusting the phases of the external reference clocks. Experiments are carried out to validate the proposed approach and the results show that the new correlator is able to detect extremely small signals buried in the noise of the measurement circuits.
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2014, Vol. 35 
